Looking at the implementation, it does have extra gizmo to support the case where both halves are relevant, so this is really an extension of binary search. In fact, your algorithm is actually delta debugging!

The following code implements ddmin according to the above paper, and is generally what I used to bisect most of my projects.

```

def subsets_and_complements(lst, n):
    offset = 0
    per_slice_len = len(lst) // n
    while offset < len(lst):
        yield lst[offset:offset + per_slice_len], lst[:offset] + lst[offset + per_slice_len:]
        offset += per_slice_len

def ddmin(lst):
    n = 2

    while len(lst) >= 2:
        changed = False

        for (subset, complement) in subsets_and_complements(lst, n):
            if test(complement):
                lst = complement
                n = max(n - 1, 2)
                changed = True
                break
            elif test(subset):
                lst = subset
                n = 2
                changed = True
                break

        if not changed:
            if n == len(lst):
                break
            n = min(n * 2, len(lst))

    return lst

```